Slip ring assembly



Sept. 30, 1958 J. B. NUGENT sup RING ASSEMBLY Filed April 21, 1955 FIG.5

FiG.4

FIGS

JNI 'ENTOR' JOHN B. NUGENT ATTYS United States Patent SLIP RING ASSEMBLYJohn B. Nugent, Winthrop, Mass., assignor, by mesne assignments, to theUnited States of America as represented by the Secretary of the NavyApplication April 21, 1955, Serial No. 503,042

4 Claims. (Cl. 339-) The present invention relates to :a slip ringassembly and more particularly to a drum type slip ring assembly that isassembled from prefabricated parts.

Various types and sizes of slip ring assemblies have been employed toconduct current between rotating and stationary elements. Slip ringassemblies are mainly of two types, there being a flat or pancake typeassembly and a drum type assembly. The present invention is of thelatter or drum type design.

Heretofore drum type slip ring assemblies which are assembled fromprefabricated parts have had either split or solid collector ringsstacked on an insulating core. The use of solid type collector ringsnormally provides for a better slip ring assembly since these rings arestronger and also since they are symmetrical they provide for a balancedconstruction that performs more satisfactorily under high speedconditions. Drum type assemblies usually consist of collector rings andinsulating rings alternately stacked on an insulating core and squeezedtogether. When an assembled unit is comprised of a large number ofrings, the thickness of each ring and insulator must be held to closetolerances so that the associated brush assemblies will aline with theproper collector rings.

The present invention provides a new and improved slip ring assemblythat can readily be assembled, and the alternate stacking of the ringsand insulators is controlled so that the brush assemblies will engagewith the proper collector rings. In the invention disclosed herein, thecollector ring spacing is fundamentally determined by the spacing ofgrooves that are cut into the core of the assembly. These grooves areaccurately located and are used to regulate the build-up of theassembly. Split locating rings are positioned axially by the grooves inthe core and these split rings are held in place radially by collectorrings. Insulating spacers separate adjacent collector rings. Theassembled core is rotatably mounted in bearings inside :a case, andbrush assemblies are positioned in the case and are spring biased toprovide contact with the collector rings. It is therefore a generalobject of the present invention to provide an improved drum type slipring assembly that can be readily assembled from fabricated parts.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawing wherein:

Fig. 1 is a top plan view of the invention;

Fig. 2 is a sectional view taken on line 2--2 of Fig. 1;

Fig. 3 is a fragmentary view of a core showing grooves therein;

Fig. 4 is a plan view of a split ring,

Fig. 5 is a plan View showing a split ring fitted inside a collectorring; and

Fig. 6 is a sectional view of a brush assembly.

Referring now to the drawing, wherein like reference charactersdesignate like or corresponding parts throughout the several views,there is shown in Figs. 1, 2, and 3 a tubular core 11 which is rotatablymounted in a case 12 by means of bearings 13. The tubular core 11, whichis preferably made of non-conducting material such as a phenolicmaterial, has grooves 14 that are cut integral therein. The embodimentshown herein has twenty-one grooves, however, it should be understoodthat a lesser or greater number could be employed without departing fromthe scope of the invention.

Split rings 15, each having first and second segments, one of which isshown in Figs. 4 and 5 of the drawing, can be fabricated from eitherelectrically conducting or non-conducting material. If the tubular core11 is made of non-conducting material then the split rings 15 can bemetallic as the tubular core 11 will prevent grounding. However, if thetubular core 11 is made of an electrically conducting material the splitrings 15 would have to be made from non-conducting material. One splitring 15 is positioned in each groove 14 and held in position radially bya collector ring 16. The outside diameter dimension of the split ring 15is greater than the outside diameter of the tubular core 11 and theinner diameter of the collector ring 16 is close fitted to the outsidediameter of the split ring 15. The collector rings 16 should befabricated from a material that has good electrical conductingproperties. An electrically insulating spacer 17 separates adjacentcollector rings 16.

Referring particularly to Fig. 2 of the drawing it can be seen that thetubular core 11 has an enlarged diameter portion 18 that fits the insidediameter of the bearing 13. An insulating washer 17 is adjacent thisenlarged diameter portion 18 and the split rings 15 are positioned inthe grooves 14 and held therein by the collector rings 16. The outsidediameter of the insulating spacers 17 is greater than the outsidediameter of the collector rings 16 and thus a track or groove is formedto keep a brush 19 in contact With the collector ring 16. An end spacer20 having an outside diameter to fit the bearing 13 is fitted over thesmaller end of the tubular core 11 and a small retaining ring 21 isseated in a groove and holds the end spacer 20, the collector rings 16,and insulating spacers 17 in position. The tubular core 11 has a flange22 that contacts the inner race 23 of one bearing 13 and a largeretaining ring 24 contacts the inner race of the other bearing 13, thuslocking the assembled tubular core 11 in position. The tubular core 11has an inner bore 25 that permits lead wires 26 to pass through and outof the radial holes 27 in the tubular core 11. Each lead wire 26 iselectrically connected, as by soldering, to a lug 28 on each collectorring 16.

Referring now to Figs. 1 and 2 of the drawing it can be seen that thereare seven rows of brush assemblies 29 extending radially of the case 12.Each row has three brush assemblies 29, making a total of twenty-onebrush assemblies 29, one brush assembly for each collector ring 16. Itis to be understood, of course, that a greater or lesser number ofcollector rings 16 and brush assemblies 29 could be used withoutdeparting from the scope of the invention, the number of collector rings16 being shown for purposes of illustration only.

The brush assemblies 29 as shown in Figs. 2 and 6 of the drawing, have abrush 19 that is secured, as by welding, to a shaft 31 which is guidedin a pair of bushings 32. A coil spring 33 fits about outside diametersof the bushings 32 and biases the brush 19 against the collector ring16. The case 12 is bored so that the bushings 32 can be slip fittedtherein and a retaining ring 34 holds the brush assemblies 29 inposition. Lead wires 26 are secured, as by soldering, to the end of theshaft opposite the brush 19.

In operation, the tubular core 11 might either be stationary and havethe case 12 rotate about the tubular core ill or the tubular core 11might be rotatable and the case 12 be stationary. In either situationwhen there is relative motion between the tubular core 11 and the case12, there will be relative motion between the collector rings 16 and thebrushes 19.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that the invention may be practiced otherwise than asspecifically described.

What is claimed is:

1. A collector ring assembly comprising a tubular core having aplurality of side by side circumferential grooves therein, a split ringhaving first and second segments in each of said grooves, electricallyconductive collector rings encircling each of said split rings, andinsulating spacers adjacent each side of said collector rings.

2. A slip ring assembly comprising a tubular core having radial holestherein, said core having a plurality of side by side circumferentialgrooves, a split ring having first and second segments in each of saidgrooves, an electrically conductive collector ring encircling each ofsaid split rings, at least one insulating washer adjacent each side ofsaid collector rings, a separate lead electrically connected to eachsaid collector ring, said leads extending through said tubular core andsaid radial holes, and contacting means for slidably engaging each saidcollector ring.

3. A slip ring assembly comprising a case, a tubular core rotatablymounted in said case, said tubular core having radial holes therein anda plurality of axially spaced circumferential grooves, a split ring ofinsulating material having first and second segments in each of saidgrooves having an outside diameter greater in dimension than the outsidediameter of said tubular core, an electrically conductive collector ringencircling each of said split rings, at least one electricallyinsulating washer adjacent each side of said collector rings, a separatelead electrically connected to each of said collector rings, said leadsextending through said tubular core and said radial holes, andcontacting means in said case for slidably engaging each said collectorring.

4. A slip ring assembly as set forth in claim 3 wherein said contactingmeans in said case comprises a brush assembly having a brush connectedto a shaft, said shaft being guided in bushings, and spring means forbiasing said brush in engaging contact with said electrically conductivecollector rings.

References Cited in the file of this patent UNITED STATES PATENTS1,756,004 Barr et al. Apr. 22, 1930 2,471,808 Baker May 31, 19492,494,244 lonard et al. Jan. 10, 1950 FOREIGN PATENTS 715,495 GermanyJan. 2, 1942

